1. Field of the Invention
The subject invention relates to valves and, more particularly, to a self draining ball valve with an adjustable bonnet and floating valve seat arrangement.
2. Description of the Invention Background
Over the years, a variety of different types of valves for controlling the flow of fluids, vapors, slurries, etc. in pipelines or conduits have been developed. Examples of such flow control valves are globe valves, gate valves, diaphragm valves and ball valves. Each of these types of valves generally have different flow and pressure characteristics due to their different configurations. For example, in a globe valve, the flowing fluid must make abrupt turns in the body, which results in a higher pressure loss than is experienced when using a gate valve wherein the fluid is permitted to flow directly through a straight opening in the valve. Globe valves are commonly used where close regulation of flow is desired and gate valves are used in applications wherein little flow resistance through the valve is desirable.
A diaphragm valve is typically equipped with a flexible member or diaphragm that is either opened or closed by pressure applied to the diaphragm. Because such valves tend to retain little or no fluid within the valve when the valve is closed, they are often employed by the pharmaceutical industry to control fluids that may culture undesirable or harmful bacteria within the valve if such fluid is permitted to remain in the valve for a period of time. However, diaphragm valves are not particularly well-suited for high fluid flow applications. Furthermore, if the diaphragm should rupture or break, there is generally no way of stopping the fluid from leaking through the valve.
Ball valves typically comprise a housing member that contains a ball-shaped flow control member that is rotatably supported within the housing by seats oriented on each side of the flow control member. A cylindrical passage is provided through the ball-shaped member to permit the fluid to flow through the valve. Ball valves, therefore, are generally suited for use in higher flow applications than are diaphragm valves. However, when a conventional ball valve is closed, fluid may be undesirably trapped within the flow control member passage and/or between the valve seats and the housing.
In addition, in many valves, and in ball valves in particular, it is desirable to be able to selectively adjust the orientation of the flow control member within the housing to compensate for seat wear and wear of the flow control member. It will be appreciated that if the flow control member is not properly supported within the valve, seat wear and wearing of the flow control member can be exacerbated. In existing valve designs, a portion of the flow control member extends through a portion of the housing to enable the flow control member to be selectively actuated. Such arrangement, however, does not permit the flow control member to be adjusted axially within the housing to ensure that the flow control member is properly supported within the housing.
Therefore, there is a need for a valve for controlling the flow of fluid within conduits that does not trap fluid within the valve when the valve is closed.
There is a further need for a valve with the above-mentioned characteristics that can accommodate higher fluid flow rates than those flow rates commonly associated with diaphragm valves of comparable sizes.
There is still another need for a flow control member that could be retrofitted into an existing ball valve for reducing the likelihood of trapping fluid within the valve when the valve is closed.
Yet another need exists for a valve wherein the axial position of the flow control member can be selectively adjusted from the exterior of the valve.
Another need exists for a valve wherein seat wear and flow control member wear can be compensated for without requiring the valve to be disassembled in order to replace the worn components.
An additional need exists for a valve that has a selectively adjustable bonnet assembly.
Still another need exists for a valve that has the above-mentioned characteristics that is relatively easy to manufacture, assemble, install, and adjust.